This invention relates to photographic illumination apparatus and more particularly to apparatus for use with motion picture or television cameras. The apparatus of the invention provides proper illumination during varying conditions and is operative to prevent excessive illumination of human objects while being highly reliable.
It is conventional practice in photography to illuminate an object by simply energizing a lamp such as a halogen lamp and to control the exposure time to compensate for variations in brightness caused by variations in the distance between the lamp and the object. Thus the lamp may be of a large size with a high luminous intensity to permit illumination of a remote object, at a large distance from the lamp, the exposure time being reduced at shorter distances.
There are problems with such prior practices which have not been fully recognized and dealt with in the prior art. An object at a short distance may be subjected to very high intensity illumination and intense heat and when a human subject is photographed, he or she may be so dazzled as to frustrate the purpose of the photographic operation. Similar problems may be encountered in attempting to photograph animals. Relative movements of subjects or objects toward or away from the lamp, or passage of objects between the lamp and an object or subject, may also present problems which are aggravated by the slow response of automatic exposure mechanisms of cameras. In photographing with television cameras, temporary blanks of the viewing screen, retention of images for sustained times and other undersirable phenomena may occur.